Comment on `thermal boundary resistance of mechanical contacts between solids at sub-ambient temperatures'

A paper by Gmelin et al examines the thermal contact resistance between copper surfaces above 1 K. It was concluded that dielectric and metallic interposers significantly increase the conductance of demountable joints. I argue that an extrapolation of electrical resistance measurements, and of thermal measurements at lower temperatures, implies that it is possible to construct considerably better joints without interposers. Moreover, dielectric interposers would reduce the conductance of such joints.